It is well known in the scientific community that ultraviolet radiation has the distinctive ability to cut electrons from an atom or molecule, thereby creating an electric charge. The amount of free electrons and total electric charge generated by ultraviolet radiation is proportional to the amount or quanta and total energy of the ultraviolet radiation applied to the object in which the electric charge is generated. The process of generating an electric charge via the exposure of an object to ultraviolet radiation does not require any external energy, a battery, or power supply, but rather requires only the ultraviolet radiation itself.
The process of cutting an electron from an atom or molecule is extremely fast, and usually less than about 10.sup.-13 seconds. Accordingly, an electric charge may be created by continuous ultraviolet radiation, as well as by pulsed ultraviolet radiation. The value of the electric charge generated by the ultraviolet radiation is generally very small, and sometimes almost unmeasurable. However, with very high intensities of ultraviolet radiation as are typically employed in industrial applications, such high intensities allow the electric charge created by the ultraviolet radiation to be measured, thus allowing for the dose of the ultraviolet radiation applied to an irradiated object to be measured.
Ultraviolet radiation measuring devices (often referred to as "dosimeters") are frequently used in various industries, including the optical lens industry, the ultraviolet curing industry, and the ultraviolet photolithography and printing industry. Prior art ultraviolet radiation measuring devices typically include a sensor for producing an electric signal under the influence of ultraviolet radiation, and a display for showing the value of the ultraviolet radiation level. In addition to the sensor and display, these prior art devices include electronic circuitry which is used to convert the electric signal produced by the sensor from the exposure thereof to the ultraviolet radiation to a form that is presentable on the display. Such electronic circuitry typically includes integrating and amplifying units, as well as other electronic components. Subsequent to the electronic integration of the signal, this "sample and hold" electronic circuitry is operable to present on the display a measured dose of the ultraviolet radiation applied to the sensor, as well as a peak intensity of the ultraviolet radiation.
However, in the prior art ultraviolet radiation measuring devices, the sensor, as well as other electronic components of the electronic circuitry, require electric power for the proper operation thereof. As such, the prior art measuring devices must also be provided with internal and/or external power supplies to provide electrical power to both the sensor and electronic circuitry thereof. Additionally, such prior art measuring devices are typically very complex in construction, and susceptible to failure due to the relative complexity of the electronic circuitry therein.
The present invention addresses and overcomes the above-described deficiencies of prior art ultraviolet radiation measuring devices by providing an ultraviolet radiation dosimeter which utilizes as its primary source of energy the ultraviolet radiation itself. In this respect, the electrical components of the present dosimeter are powered by the energy of the measured ultraviolet radiation, with an external power supply being needed only if a digital or analog electrometer is employed in the dosimeter for purposes of powering the display thereof. However, since the display consumes so little power, the external power needs of the present dosimeter can be served for a prolonged time frame by a simple coin lithium battery. The need for any external power supply whatsoever may be completely eliminated in the present dosimeter by utilizing a standard repulsive charge electrometer as an alternative to a digital or analog electrometer. The present dosimeter is also compact and easy to use, and significantly more simple and cost effective to manufacture than those known in the prior art.